1. Field of the Disclosure
This disclosure relates to a backlight unit adapted to implement uniform brightness (or luminance) and an LCD device having the same.
2. Description of the Related Art
It is the trend that liquid crystal display (LCD) devices are widening their application fields because of their features, such as their light weight, slimness, a low driving voltage, and so on. This trend is confirmed in the ways in which the LCD devices have been applied to office automation equipment, audio equipment, video equipment, and so on. The LCD device controls a transmitting amount of light on the basis of image signals applied to a plurality of control switches, in order to display a picture.
The LCD device, which is not self-luminescent, includes a backlight unit irradiating light on the rear surface of an LCD panel in which a picture is displayed. The backlight unit is classified as either an edge type or a direct type in accordance with the disposition of its light source.
The edge type backlight unit includes a light source which is positioned at one edge of the LCD panel. Also, the edge type backlight unit applies light emitted from the light source to the entire surface of the LCD panel using a light guide panel. On the other hand, the direct type backlight unit includes a plurality of light sources arranged opposite the rear surface of the LCD panel. These plural light sources directly apply light to the rear surface of the LCD panel. As contrasted with the edge type backlight unit, the direct type backlight unit has advantages such as a higher brightness and a wider emission dimension of the plural light sources.
In addition, the backlight unit becomes larger in size corresponding to the increased size of the LCD device. Accordingly, the direct type backlight unit is generally applied to the LCD device. The LCD device employing the direct type backlight unit generally forces a plurality of light sources to be arranged separately from the rear surface of an LCD panel at a fixed interval.
However, as the plural light sources are disposed just under the LCD panel, the LCD device including the direct type backlight unit causes the plural light sources to be projected enough to be seen with the naked eye on the LCD panel.
To address this matter, the LCD device can increase the distance between the light sources and a diffusion plate disposed above them. In this case, the brightness difference between regions in which the light source is disposed and those where it is not can be improved. In other words, the LCD device can obtain uniform brightness. On the other hand, it is difficult to thinly manufacture an LCD device including the direct type backlight unit.